Finger Safety Terminals and Gloves

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Tarbaby

Member
I have a panel constructed using finger safe terminals. Trouble shooting using a voltmeter with 600 volt fusing and insulated probes(typical fluke DMM), or solenoid tester is going to be performed. The following is also known:
1. The Arc Flash hazard by analysis and NFPA 70E tables is 0.
2. The voltage in the panel is a maximum of 120VAC.
3. The control panel is constructed with all finger safe items.
4. If components in the control panel are to be replaced lock out tag out procedures require the control panel to be de-energized.

NFPA 70E Table 130.2 has the prohibited approach boundary at ?avoid contact? for conductive objects unless the user is insulated. OSHA has a similar approach distance.

I have asked a couple of manufactures and they keep confusing the answer with arc flash PPE.

Questions:
1. Can testing be done without wearing voltage rated gloves?
2. What if the same conditions except the voltage is greater than 300volts ar voltage rated gloves required?
3. If the answer to the first question is no, why would you use finger safe terminals?
4. If the answer to the second is no, why do they make finger safe terminals for 600 volt devices?
 

cornbread

Senior Member
Article 100 definitions

Working on (energized electrical conductors or circuit parts):

Coming in contact with energized electrical conductors or circuits parts with hands, feet, or other body parts, with tools, probes, or with test equipment, regardless of the protective equipment a person is wearing...
 

billsnuff

Senior Member
If the analysis has been done and you have an HRC of 0, then 130.7(C)(10) indicates leather gloves (AN).

But to go a step further, what does your program require? Are you using an EWP? If so, what is the justification?

The basis of 70E is your safety and the emphasis is to work deenergized, unless 'infeasible'.
 

Tarbaby

Member
I will take the respones to the first two questions as no, I still wonder about the third, why are finger safe item made? Also, why do the manufactures put the covers over breakers with holes only the probes of a meter will fit through?
 

billsnuff

Senior Member
just to clarify

just to clarify

there are two seperate issues here:

shock hazard

arc flash

while the finger guard may protect from the first, is it adequate for the second?

what is the reason for working live? (just curious, really)
 

Tarbaby

Member
Industrial control circuits are hard to trouble shoot if manufactures don't wire each switch with an indicator light to indicate the switch is made. Also many devices require power to operate so they can energize the relay contact to provide the input to the control system(fail safe).

But the statement that "it may solve the first(shock hazard)" is what I would think was the reason for finger safe terminals. I can reduce the arc flash hazard by spending more on overcurrent methods. But trying to trouble shoot a control system that is deenergized is almost impossible. Everybody skirts around saying it can eliminate the need for PPE when the arc flash hazard isn't a problem. So goes back to the basic question, why use them if it doesn't allow you to engineer out the safety hazard.
 

Jraef

Moderator
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Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
It should also be noted that the term "finger safe" does not appear in any US regulatory agency publications with regards to electrical equipment (as far as I know). It is a term that came along with the influx of European electrical equipment where there is a specific requirement that control devices (and power devices under a certain amperage rating) are to be "Finger Safe" as per a very specific test procedure in IEC 60529, IP20 (and above). It fell into common use here but has no "official" standing.
 
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